When selecting a paint colour for decorating a room, it is often the case that the customer will wish to match the paint colour to a colour of a particular item to be contained in the room such as an item of furniture, or soft furnishings such as cushions, sofas, curtains, or the like. Paint producers typically provide large colour palettes, and detailed colour displays are provided in paint retailers, to enable customers to select a colour. Colour sample cards are available for the user to take home and match to the item to which the colour is to be matched. However, conventionally this requires the customer to visit a paint retailer store, collect colour cards, take the colour cards home, and then attempt to compare the colour samples on the colour cards with the colour of the item to be matched. The customer must then return to the store, typically buy tester pots of paint, return home, use the tester pots of paint, and then ultimately make a purchasing decision. In addition, such conventional techniques rely upon the individual customer's perception as to which is the best matching paint colour. However, it is well known that colour perception varies significantly from person to person, such that a matching colour to a sample selected by one person will not appear to be a matching colour to another person.
One potential solution to this problem is to try and match colours electronically, using a digital image. In this regard, nowadays domestic users typically have many digital image capture devices at their disposal, in the form of digital cameras, or camera equipped mobile telephones.
However, the colour capture characteristics of typical domestically available image capture devices, such as digital cameras, mobile telephones or the like, vary significantly from device to device and hence accurate colour capture is not typically possible. Specialist spectrophotometer devices are available that can accurately measure colour, but these are beyond the means of most domestic consumers. Typical domestic image capture devices will capture an image and represent colour using RGB pixel values. Typically 16 bit or 24 bit RGB is used. Where 16 bit values are used, each of the red and blue channels typically has five bits associated therewith, whereas the green channel has six bits associated therewith. In this respect, the human eye is more sensitive to green colours than it is to red and blue colours, and hence a greater number of green colours are detectable. Where 24 bit colour is used, then this equates to eight bits, or 256 colours, per colour channel.
However, because of the above noted differences in image capture devices in capturing colour accurately, and also in image reproduction devices such as monitors and the like in reproducing colours, RGB values of colour are not regarded as standard values. Instead, there are fixed standards defining colour laid down by the Commission International De L'Eclairage (CIE) such as the CIE tristimulus values X, Y, Z, or the so-called CIELAB values (L*, a*, b*). CIELAB values are related to the tristimulus values XYZ using a known mathematical formula. The tristimulus XYZ values are themselves related to the wavelengths present in a particular colour.